Maricopa County Sheriff Joe Arpaio, the darling of conservatives and bane of immigration rights activists, was the apparent target of an explosive device that was intercepted and disabled, Arizona officials said on Friday.

The device, which is being examined for clues, also comes after weeks of attacks on police officers and prosecutors. Arpaio, who is also the subject of a recall campaign, has condemned the attacks on fellow elected law enforcement officials.

Throughout his 20-year tenure, Arpaio has been no stranger to threats. Some have turned out to be hoaxes and some such as those in the 2012 election campaign were real enough to lead to arrests.

The current threat seems to be the first involving what the department has called an explosive device, though its exact nature is still under investigation, along with possible suspects.

A suspicious package was picked up at a rural post office on Thursday and sent to the Flagstaff post office. There, a worker contacted authorities who tested and found it had leaked gunpowder. The package was examined by X-ray and disabled, officials said.

“The box, which was addressed to Arpaio at his downtown Phoenix headquarters, was X-rayed and was determined to contain an explosive device inside, according to Flagstaff police,” the Maricopa sheriff’s office said in a statement emailed to reporters. “A bomb team was deployed and the device has been neutralized.”

Arpaio, who describes himself as America’s toughest sheriff, is an icon in the conservative world for his strong efforts to block immigrants from illegally entering the country along his state’s border. He also is known for dressing jail inmates in pink underwear.

Critics have accused him of profiling Latinos for selective and harsh treatment by his patrols. He has also been the target of federal probes, none of which has led to any charges.

No sooner had Arpaio taken office on January for a sixth term, critics launched a recall campaign.

Arpaio also condemned the recent attacks on law-enforcement officials including a state prison chief, prosecutors and officers.

“What I struggle with is understanding the whys behind these recent murders of law enforcement officials in Colorado, Texas and now West Virginia,” Arpaio said. “The brazenness of these acts is confounding. Inside one year, two of my deputies were shot, one killed and one nearly killed and now elected law enforcement officials across the nation seem to be being targeted.”